Practice question

For the Washington CDL Air Brakes knowledge test, what is the role of the one-way (check) valve at the supply tank?

  1. It releases excess pressure
  2. It keeps air from flowing back from the storage tanks to the compressor if the compressor or supply line fails
  3. It dries the air
  4. It activates the parking brake

Answer: B — It keeps air from flowing back from the storage tanks to the compressor if the compressor or supply line fails

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